Dan Magill's telephone rang Wednesday morning. When he answered it the voice on the other end of the line said, "Hey, Coach, it's John."

Magill, the octogenarian majordomo of Georgia tennis, replied, "John who?" The question is sweeping through the U.S. Open grounds this week like a welcome breeze, but Magill ended up feeling sheepish for asking.

The caller was John Isner, who in the span of three months has gone from being a big man on campus at Athens, Georgia, to the biggest story of the Open's first week. Magill, recovering quickly, said, "Aren't you supposed to be playing now?"

Later in the day, Isner defeated Rik De Voest in a second-round match to set up a third-round meeting Saturday with the world No. 1, Roger Federer. But Isner made time to thank Magill for the congratulatory voice-mail message he left after Isner's first-round victory against No. 26 Jarkko Nieminen.

"That's the way he is," Magill said by telephone after recounting his conversation with Isner. "He's just as fine a boy as I've ever known."
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Isner's booming first serve turns people's heads, but his second serve is what Nieminen remarked on after their match.

Manuel Diaz, who coached Isner at Georgia and is at the Open this week to cheer him on, said: "Right now he's on Cloud 9. The way he's hitting his ground strokes, he's on a totally different level than he was a month ago. That's all confidence."

Isner was easy to overlook when he arrived at Georgia from Winston Salem, North Carolina, as a freshman.

"One of the first things I told him was, 'You need to be a serve and volleyer,' " Diaz said. "I expected him to question it or get frustrated. But that was one thing off the bat that set him apart. He bought into it right off the bat."

Toward the end of his sophomore year, Isner's game began to take shape. Between April 8, 2005, and March 11, 2007, he did not lose a completed dual match, stringing together 46 victories before losing in three sets on the road to Florida's No. 1 player, Jesse Levine, who lost in the first round here to Nikolay Davydenko.

People used to flock to Isner's college matches to behold his serve. Magill, who coached the Bulldogs for 34 years before retiring in 1995, said he had never seen one fiercer or more fluid. "He has a tremendous angle and perfect form," Magill said.

Magill said he sat in the stands during Bulldogs matches and shouted before each of Isner's service games, "Give 'em Big Bertha!" It was a reference to a German railway gun used in World War I, which, as Magill wryly pointed out, he is old enough to remember.

In late May, Isner, a four-time all-American who stands nearly 6-foot-10, or 2.08 meters, and weighs 235 pounds, or 107 kilograms, advanced to the singles final at the NCAA championships, where he lost in three sets to Somdev Devvarman of Virginia. "Seems like forever ago," Isner said. "I've done so much since then."

After leaving school 12 credits short of a degree to turn pro, Isner advanced to the final of his second ATP event, in Washington. He lost to Andy Roddick in the championship but gained a lot of confidence with victories along the way over the former top-five players Tim Henman and Tommy Haas.

Travis Helgeson, a college teammate and close friend of Isner's, has spoken to him this week. "Just talking to him, he feels like he can beat anyone right now," Helgeson said by phone.

Isner faces a tall order in beating Federer, who is aiming for his fourth U.S. Open title. "I'm going to have to attack, try to get to the net, make the points shorter," he said.

"If I go in that match not believing I'm going to win, just happy to be out there, you know, he's going to smell that blood and just attack," Isner said. "I'm not saying I'm going to win, but I'm going to believe."